Analyzing the effects of type I interferons in the enterovirus-infected heart

 描述（由申请方提供）：病毒性心肌炎是一种相对常见的疾病，有时严重，可能致命，最常见的原因之一是肠道病毒柯萨奇病毒B3（CVB 3）。心脏的CVB 3感染是高度集中的，即使在缺乏完整的适应性免疫系统的小鼠中也是如此，这表明先天免疫可能会抑制病毒。I型干扰素（T1 IFN）是一个明显的候选者，并且已知对肠道病毒性心肌炎的结果有积极影响。然而，我们对T1 IFN的作用是如何介导的还不了解。例如，一个非常受人尊敬的小组认为，T1 IFN甚至可能不在心脏内起作用，它们的心脏保护作用可能是间接的，是由于抑制了其他器官中的病毒复制。我们已经产生了小鼠，其中T1 IFN受体（T1 IFNR）可以在体内特异性地从心肌细胞中消除，我们未发表的数据明确表明，T1 IFN确实，事实上，直接作用于心肌细胞在CVB 3感染，并在病毒滴度和CVB诱导的疾病中发挥重要作用。但仍存在许多问题。它们是如何做到这一点的-在感染的（和未感染的）心肌细胞中，哪些基因被T1 IFN激活？我们将确定心肌细胞的基因，直接响应T1干扰素信号在体内。CVB 3还导致慢性心肌炎和扩张性心肌病，这与心脏中的RNA持续存在有关，我们的诱导型基因敲除模型在这方面具有关键的实验优势;我们可以在遗传完整的小鼠中建立持续的CVB 3感染，这些小鼠不会发生疾病，然后将T1 IFN信号传导到心肌细胞中，以询问：这些小鼠现在是否发生疾病，即对慢性心肌炎/ DCM的抵抗/易感性是否与心肌细胞中的T1 IFN信号有关？我们的初步数据表明，T1 IFN在心脏CVB 3感染期间的作用可能是双相的，并且我们假设这两个时间阶段是由T1 IFN的不同细胞来源定义的。因此，目标2和3将我们的重点扩展到解决T1 IFN的生产。哪些细胞是T1 IFN的来源？浆细胞样DC（pDC）是明显的候选者，但最近的工作对它们在病毒感染期间的真实体内作用提出了疑问，并且还表明TLR 3依赖的T1 IFN的产生在控制病毒感染中可能更重要。该提案有三个具体目标目标1.研究急性和持续CVB 3感染时心肌细胞中1型IFN信号转导的体内后果。目标2.评价pDC在CVB 3感染过程中的作用确定TLR 3在CVB 3诱导的心肌炎中起关键作用的原因。

 DESCRIPTION (provided by applicant): Viral myocarditis is a relatively common, sometimes severe, and potentially fatal disorder, and one of the most frequent causes is the enterovirus coxsackievirus B3 (CVB3). CVB3 infection of the heart is highly focal, even in mice lacking an intact adaptive immune system, suggesting that innate immunity may hold the virus in check. Type I interferons (T1IFNs) are an obvious candidate, and are known to positively affect the outcome of enteroviral myocarditis. However, there is much that we do not know about how the effects of T1IFNs are mediated. For example, one very well-respected group has argued that T1IFNs may not even act within the heart, and that their cardioprotective effects may be indirect, resulting from the suppression of viral replication in other organs. We have generated mice in which the T1IFN receptor (T1IFNR) can be ablated in vivo specifically from cardiomyocytes, and our unpublished data show unequivocally that T1IFNs do, in fact, act directly on cardiomyocytes during CVB3 infection, and play a substantial role in viral titers and CVB-induced disease. But many questions remain. How do they do this - what genes are activated by T1IFNs in infected (and in uninfected) cardiomyocytes? We shall identify the cardiomyocyte genes that are directly responsive to T1IFN signals in vivo. CVB3 also causes chronic myocarditis and dilated cardiomyopathy, which are related to RNA persistence in the heart, and our inducible gene knockout model confers a key experimental advantage in this regard; we can establish persistent CVB3 infection in genetically-intact mice that do not develop disease, and afterwards ablate T1IFN signaling into cardiomyocytes, to ask: do these mice now develop disease, i.e. might resistance/susceptibility to chronic myocarditis / DCM be related to T1IFN signaling in cardiomyocytes? Our preliminary data indicate that the effects of T1IFN during CVB3 infection of the heart may be biphasic, and we hypothesize that the two temporal phases are defined by differing cellular sources of the T1IFNs. So, Aims 2 and 3 extend our focus to address the production of T1IFNs. What cells serve as the source of the T1IFNs? Plasmacytoid DCs (pDCs) are obvious candidates, but recent work has raised questions about their true in vivo role during viral infection, and also has shown that TLR3-dependent production of T1IFNs may be more important in controlling virus infection. The proposal has three Specific Aims Aim 1. To investigate the in vivo consequences of type 1 IFN signaling in cardiomyocytes during acute and persistent CVB3 infection. Aim 2. To evaluate the role of pDCs during CVB3 infection Aim 3. To determine why TLR3 plays a key role in CVB3-induced myocarditis.